Editor: Update Navigation Overlay template part description.

Refines the Navigation Overlay template description to remove the "full-screen" assumption and clarify that the overlay can be toggled open and closed.

Follow-up to [61609].

Props get_dave, scruffian, wildworks.
See #64589.

git-svn-id: https://develop.svn.wordpress.org/trunk@61734 602fd350-edb4-49c9-b593-d223f7449a82

Author: t-hamano

src/wp-includes/block-template-utils.php

@@ -103,7 +103,7 @@ function get_allowed_block_template_part_areas() {
 			'area'        => WP_TEMPLATE_PART_AREA_NAVIGATION_OVERLAY,
 			'label'       => _x( 'Navigation Overlay', 'template part area' ),
 			'description' => __(
-				'The Navigation Overlay template defines a full-screen overlay area that typically contains navigation links and can be toggled on and off.'
+				'The Navigation Overlay template defines an overlay area that typically contains navigation links and can be toggled open and closed.'
 			),
 			'icon'        => 'navigation-overlay',
 			'area_tag'    => 'div',